1. Field of the Invention
The present invention relates to a wedge assembly restraint featuring a retainer clip. The wedge assembly restraint has particular utility in connection with the assembly, transportation, and installation of a pipe junction holder such as the holder described in U. S. Pat. No. 4,092,036 to Sato et al., the entire disclosure of which is incorporated herein by reference.
2. Description of Related Information
It is frequently desirable to connect a pair of axially aligned pipes such that a tight fit and suitable seal are formed therebetween. It is also desirable to prevent the disengagement that could occur when pressure is applied in the axial direction.
It is known in the prior art to employ special pipes and a pipe junction holder to accomplish this purpose. A first pipe is adapted to be received within a second pipe having an enlarged mouth, a packing cavity, and a terminal flange. An annular pipe junction holder is connected to both the outer surface of the first pipe and the terminal flange of the second pipe, so as to hold the two pipes together.
The Sato patent discloses a pipe junction holder comprising a substantially annular body having an annular projection. The annular body is connected to the terminal flange of the second pipe using conventional flange-mating means, such as a series of axially aligned bolts placed through holes in the terminal flange and engaged with holes formed in the wall of the annular body. The annular projection abuts against packing placed in the packing cavity of the second pipe.
The pipe junction holder is connected to the first pipe using a plurality of clamping assemblies uniformly distributed around the annular body. The clamping assemblies comprise a clamping block and a wedge assembly. The Sato patent discloses that at least three clamping assemblies are employed although two clamping assemblies may be used in practice.
Each clamping block is defined by a plurality of integral sidewalls, a radially outer wall, and an open mouth, wherein the sidewalls include a front sidewall integral to the annular body and a rear sidewall opposite the front sidewall. The clamping block extends axially away from the annular body of the pipe junction holder, such that the open mouth faces the peripheral wall of the first pipe when the pipe junction holder is installed thereon. The radially outer wall is inclined with respect to the longitudinal axis of the pipe and has an elliptical hole therein.
Each wedge assembly comprises an internally reverse-threaded pipe-pressing member and a collar bolt.. The collar bolt has an annular flange formed integral with its shank and is threaded therebelow to engage the pipe-pressing member. The upper portion of the collar bolt is unthreaded.
In operation of the pipe junction holder, the pipe-pressing member is partially engaged on the threaded side of the collar bolt, below the annular flange. -The collar bolt and engaged pipe-pressing member are received within the clamping block such that the annular flange slidably abuts the internal surface of the radially outer wall, and such that the upper portion of the collar bolt protrudes through the elliptical hole. A rubber spacer is placed between the wedge assembly and the rear sidewall of the clamping block to keep the wedge assembly in a forward orientation during installation.
Because the pocket of the clamping block is shaped so as to prevent the pipe-pressing member from turning, and because the annular flange prevents radially outward motion of the collar bolt, rotating the upper portion of the collar bolt causes the pipe-pressing member to travel down the bolt shank and towards the pipe. By, employing a pipe-pressing member with edges that can bite into or penetrate the peripheral wall of a pipe, and by turning the bolt in each clamping block to a suitable torque, the pipe junction holder is secured to the pipe.
Proper torque of the wedge assemblies may be obtained by providing a nut designed to shear at a predetermined torque (hereinafter, a "twist-off" nut). A suitable twist-off nut is disclosed in U.S. Pat. No. 4,627,774 to Bradley, the entire disclosure of which is incorporated herein by reference.
It is desirable to restrain a wedge assembly in its clamping block prior to installation and in the event the pipe junction holder is removed or reinstalled. Once attached, a twist-off nut restrains a wedge assembly in its clamping block since the head of the nut is of greater diameter than the elliptical hole in the clamping block. However, prior to installation of the twist-off nut and after the nut is sheared off, wedge assemblies can fall out of their clamping blocks and can get lost or damaged as a result. Loss or damage can also occur where the twist-off nut is inadvertently sheared off due to abrupt shock or other trauma during transportation, storage, or installation.
The loss of wedge assemblies prior to assembly of the pipe junction holder and in the event the pipe junction holder is removed or reinstated is a source of irritation, inconvenience, and expense for end users of the pipe junction holder. In addition, during the initial assembly of the pipe junction holder, the lack of an independent restraint on the wedge assemblies prior to installation of the twist-off nuts prevents preassembly of the wedge assemblies into the pipe junction holder, resulting in decreased efficiency.
In the past, wedge assembly restraints suffered from low reliability, excessive expense, and burdensome manufacturing requirements. For example, the inclusion of the retainer ring disclosed in the Satopatent added to the expense of the device and increased the processing of the individual parts. In addition, use of the retainer ring added expense and inefficiency at the manufacturing stage because a press was required to assemble the parts. Machining grooves into the collar bolts to provide a positive stop for the retainer rings provided a consistent hold but also added two significant steps to the manufacturing process.
A need exists, therefore, for a simple and inexpensive device that can reliably restrain a wedge assembly in a clamping block of a pipe junction holder. Such a device should restrain the wedge assembly from preassembly through installation or reinstallation, and should function whether or not a twist-off nut is in place. Also, such a device should not hinder operation of the pipe-pressing member either in wedge actuation during installation or movement of the pipe-pressing member during operation.